From 94b31c1db7176d7e37ec836747e50a7d89a06c65 Mon Sep 17 00:00:00 2001
From: wareya <wareya@gmail.com>
Date: Wed, 18 Oct 2023 00:53:11 -0400
Subject: [PATCH] Optimize cubic hermite algorithm in
 AudioStreamPlaybackResampled

---
 servers/audio/audio_stream.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/servers/audio/audio_stream.cpp b/servers/audio/audio_stream.cpp
index e2c86869116..ece088a694b 100644
--- a/servers/audio/audio_stream.cpp
+++ b/servers/audio/audio_stream.cpp
@@ -173,12 +173,12 @@ int AudioStreamPlaybackResampled::mix(AudioFrame *p_buffer, float p_rate_scale,
 		}
 
 		float mu2 = mu * mu;
-		AudioFrame a0 = 3 * y1 - 3 * y2 + y3 - y0;
-		AudioFrame a1 = 2 * y0 - 5 * y1 + 4 * y2 - y3;
-		AudioFrame a2 = y2 - y0;
-		AudioFrame a3 = 2 * y1;
+		float h11 = mu2 * (mu - 1);
+		float z = mu2 - h11;
+		float h01 = z - h11;
+		float h10 = mu - z;
 
-		p_buffer[i] = (a0 * mu * mu2 + a1 * mu2 + a2 * mu + a3) / 2;
+		p_buffer[i] = y1 + (y2 - y1) * h01 + ((y2 - y0) * h10 + (y3 - y1) * h11) * 0.5;
 
 		mix_offset += mix_increment;